The ionic residues of the chymotrypsins, hemoglobins and cytochrome c are being characterized by potentiometric and thermal techniques. Many model compounds, singly or as mixtures will be processed and the data evaluated. On satisfactory completion of this phase we intend to apply the knowledge gained to he more complex polymeric system. We hope to be able to isolate and study the ionic residues as sets of groups or individual groups as a means toward understanding the variety of biological processes which proteins are capable of performing.